Pour enough oil to coat the bottom of a cast iron or other heavy-bottomed skillet. There should be enough oil to put a thermometer in the skillet, but not covering the okra. Heat to 360*.Cut both ends of the okra off. Slice into 1/4-1/2 inch slices. Rinse for 15 seconds. Mix cornmeal, salt and cayenne together in a shallow bowl. Coat wet okra in the cornmeal mixture, and drop into hot oil. Do not stir. Cook for two minutes.Add onions to the skillet, and stir together with okra. Cook for another two minutes. Remove okra from oil, and drain on a paper towel lined cooling rack. Sprinkle salt over the hot okra. It is recommended that you fry the okra in batches. Serve hot.